doc-guide: kernel-doc: move in-line section to be after nested struct

doc-guide: kernel-doc: move in-line section to be after nested struct

We want to give some examples about how to do in-line comments
for nested structs. So, move it to be after nested structs/unions
chapter.

The section content was not changed on this patch.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>